Explanation:
Box 1: Azure AD Privileged Identity Management
Privileged Identity Management provides time-based and approval-based role activation to mitigate the risks of excessive, unnecessary, or misused access permissions on resources that you care about. Here are some of the key features of Privileged Identity Management:
Provide just-in-time privileged access to Azure AD and Azure resources
Assign time-bound access to resources using start and end dates
Require approval to activate privileged roles
Enforce multi-factor authentication to activate any role
Use justification to understand why users activate
Get notifications when privileged roles are activated
Conduct access reviews to ensure users still need roles
Download audit history for internal or external audit
Prevents removal of the last active Global Administrator role assignment Box 2: Azure Managed Identity Managed identities provide an identity for applications to use when connecting to resources that support Azure Active Directory (Azure AD) authentication. Applications may use the managed identity to obtain Azure AD tokens. With Azure Key Vault, developers can use managed identities to access resources. Key Vault stores credentials in a secure manner and gives access to storage accounts.
Box 3: Azure AD Privileged Identity Management
Privileged Identity Management provides time-based and approval-based role activation to mitigate the risks of excessive, unnecessary, or misused access permissions on resources that you care about. Here are some of the key features of Privileged Identity Management:
Provide just-in-time privileged access to Azure AD and Azure resources
Assign time-bound access to resources using start and end dates
Reference:
https://docs.microsoft.com/en-us/azure/active-directory/privileged-identity-management/pim- configure
https://docs.microsoft.com/en-us/azure/active-directory/managed-identities-azure- resources/overview

Explanation:
Box 1: Azure AD
The Azure AD server issues tokens (access & refresh token). See step 5 below in graphic.
OAuth 2.0 authentication with Azure Active Directory.
The OAuth 2.0 is the industry protocol for authorization. It allows a user to grant limited access to its protected resources. Designed to work specifically with Hypertext Transfer Protocol (HTTP), OAuth separates the role of the client from the resource owner. The client requests access to the resources controlled by the resource owner and hosted by the resource server (here the Azure AD server). The resource server issues access tokens with the approval of the resource owner. The client uses the access tokens to access the protected resources hosted by the resource server.

Box 2: A web API
Delegated access is used.
The bearer token sent to the web API contains the user identity.
The web API makes authorization decisions based on the user identity.
Reference:
https://docs.microsoft.com/en-us/azure/active-directory/fundamentals/auth-oauth2
https://docs.microsoft.com/lb-lu/azure/architecture/multitenant-identity/web-api

With Azure Blueprints, the relationship between the blueprint definition (what should be deployed) and the blueprint assignment (what was deployed) is preserved. This connection supports improved tracking and auditing of deployments. Azure Blueprints can also upgrade several subscriptions at once that are governed by the same blueprint.
Reference:
https://docs.microsoft.com/en-us/answers/questions/26851/how-is-azure-blue-prints-different-from-resource-m.html

Azure Resource Policy Definitions can be used which can be applied to a specific Resource Group with the App Service instances.
Reference:
https://docs.microsoft.com/en-us/azure/governance/policy/overview